Method for producing a curved tubular connection element

ABSTRACT

The invention relates to a method for producing a curved tubular connection element, having at least the following production steps: machining a linearly running metal tube piece ( 10 ) with a specifiable length while incorporating connection geometries ( 12, 14 ) for receiving separate connection parts ( 18, 20 ) which are used to connect a media-conducting piping; carrying out a bending process for the tube piece ( 10 ), which is produced by being machined in the aforementioned manner, with a specifiable bending radius, preferably up to 90 degrees; and attaching each connection part ( 18, 20 ) to the respective end-face tube piece ( 10 ) connection geometry ( 12, 14 ) which can be paired therewith.

The invention relates to a method for producing a bent tubular connection element.

From DE 10 2007 016 766 A1 a device for injection molding pipe elbows, having a bent section with a circular arc-shaped centerline and a constant internal cross-section and cylindrical connection nozzles adjoining on both sides, having a multi-part injection mold consisting of a permanent mold of outer moldings and core parts, which can be divided into at least two outer mold parts in the plane of the circular arc-shaped center line of the manifold section, which outer mold parts form a mold cavity and which permanent mold comprises the at least three movable core parts is known.

A disadvantage of the relevant prior art is that a separate injection mold has to be manufactured for every shape of a pipe bend and for every bending radius of the pipe elbow, which is expensive and entails high production cost.

From DE 27 14 782 A1 a method for the manufacture of pipe elbows, in particular made of thin-walled material, is known, wherein a straight pipe section is stretch-pressed over a stretching device such that the original wall thickness of the pipe section is variably reduced over the circumference of the pipe, wherein the straight pipe section, due to the varying material stretching, is deformed into a pipe elbow whose neutral fibers, in which the original wall thickness is maintained, are located in the inner pipe bend.

In the known solution soft-soldered, brazed or welded, spot-welded, beaded and seamlessly drawn pipe sections are used for the actual bending process, wherein, depending on the desired shape of the bend, elongations up to 180% and reductions in wall thickness of up to 60% of the material used for the pipe elbow occur. Due to the at least partial reduction of the original wall thickness of the initially rectilinear pipe section during the bending process, an overall weakening of the input material occurs; as a result the relevant solution is not suitable for high-pressure applications.

Based on this prior art, the invention addresses the problem of providing a method such that a bent tubular connection element, which is also suitable for high-pressure applications, is obtained at low production costs and reduced manufacturing effort.

A method having the features of patent claim 1 in its entirety solves this problem.

Due to the fact that the manufacturing steps below are provided in the method according to the invention:

-   -   Performing a machining operation for a metallic, rectilinear         pipe section of predeterminable length, including connection         geometries for receiving separate fittings to connect         media-carrying pipework,     -   Performing a bending process for the pipe section machined thus         having a predetermined bending radius, preferably of up to 90         degrees, and     -   Mounting the respective fitting to the assignable connection         geometry at the end of the pipe section, preferably by means of         beading, pressing, welding, screwing or clamping,         a pressure-resistant pipe elbow or bending tube as a connection         element in the context of a connection pipework can be achieved         at low cost and manufacturing effort. Because in the initial         state, a rectilinear pipe section including its connection         geometries is achieved by machining, in particular by lathing, a         constant pipe wall thickness is achieved in the connecting         region of interest where the fittings are located and         essentially also after the bending process, such that in this a         way due to the machining of the pipe section relatively thin         wall thicknesses can be implemented in the area of the         connection geometries, which are still sufficient to subject the         connector to high pressure applications.

The main advantage of the arc-type design is the increased flow rate at the identical cross-section and correspondingly reduced flow resistance values of the media compared to corner angles or for hollow screws (about 20 to 30%) and compared to other bent connections, where cross-sectional constrictions must occur due to production and assembly methods. Furthermore, the method solution according to the invention and the resulting bent piece can be implemented in a cost-effective manner.

Furthermore, a stretching mandrel device, as shown by way of example in DE 27 14 782 A1, can preferably be used to achieve a plurality of different, freely selectable bending radii for the tubular connection element using only one single production device, which is superior to injection molding where a separate mold is required for every individual bending radius of a bent pipe section or pipe elbow produced and results in a significant cost reduction.

In addition, the bending process for the pipe section may be a cold forming process, wherein embrittlement of the input material for the initially machined pipe section is prevented, which in turn adds to the high-pressure resistance.

As the connection geometries can be produced by machining before the actual bending process to achieve the bent connecting piece or pipe elbow, an increased variability is created in this respect as well, because a multiplicity of different fittings can be attached to standardized connection geometries for the purpose of a subsequent connection of the connection element to an existing pipework, which may consist of fixed or flexible hose as part of the former, for example in the shape of a pneumatic distribution system. Overall, the method for producing the connection element and the connection element itself accomplish a partially modular approach permitting a multiplicity of implementation options in the context of the aforementioned media or fluid-conducting connection technology. This is without parallel in the prior art.

Further advantageous embodiments of the method solution according to the invention are the subject matter of the further dependent claims. A connector manufactured based on the method is the subject matter of the patent claim.

Below, the solution according to the invention is explained in more detail by means of exemplary embodiments of a connector according to the drawing. In the schematic figures, which are not to scale,

FIG. 1 shows, partially in longitudinal section, partially in front view, a rectilinear pipe section of predeterminable length having connection geometries arranged at the end;

FIG. 2. shows the pipe section bent by 90° according to FIG. 1;

FIG. 3. shows the bent pipe section according to FIG. 2 including attached fittings and partially shown hose;

FIG. 4. shows, partly in longitudinal section, partly in frontal view, the solution according to FIG. 3, but without inserted hose;

FIG. 5. shows, partially in longitudinal section, partially in front views, the bent pipe section according to FIG. 2 with different types of fittings as shown above; and

FIG. 6. shows a representation corresponding to FIG. 5 having the same fittings, but having a shortened pipe section and a different, smaller bending radius of 45°.

FIG. 1 shows, partially in longitudinal section, partially in front view, a rectilinear pipe section 10 of predeterminable length having connection geometries 12, 14 arranged at the end. The pipe section 10 consists of a conventional metal material and is preferably achieved by lathing in a machining manner from the solid, wherein, except for the connection geometry 12, the pipe section 10 has a constant inner diameter. If reference is made to a high-pressure resistant design, this includes normal-pressure resistant applications. In particular in the case of the pneumatic applications mentioned below, the pressure values to be controlled regularly amount to up to 24 bar.

FIG. 2 shows the pipe section 10 of FIG. 1 in the bent state, wherein the bend in this case is 90°. Consequently, the two connection geometries 12, 14 at the two opposite end areas of the rectilinear pipe section 10 receive between them a pipe segment 16 having a constant outer diameter, which is bent and which in the bending process as shown in FIG. 2 is centrally provided with the largest curvature. As FIG. 1 further shows, both connection geometries 12, 14 are designed different from one another from a machining point of view in order to be able to accommodate different fittings 18, 20 according to the illustration of FIG. 3 et seq. To receive such fittings 18, 20, provision is made that two flange-like widenings 22, 24 of the connection geometries 12 and 14 adjoin the pipe segment 16 of the pipe section 10 having a constant diameter on both sides, which widenings are formed as the widest points of the connection geometries, wherein the diameter of every connection geometry 12, 14 is reduced towards the free end 26, 28 of the pipe section 10 with respect to this widest point 26 or 28.

As the illustration of FIG. 3 shows, the respective assignable fitting 18 and 20 is then set onto the connection geometry 12, 14 of the pipe section 10 according to FIGS. 1 and 2 and connected to the pipe section 10 and its connection geometries 12 and 14, respectively. The relevant fittings 18, 20 serve amongst others the inclusion of hoses 30, which are preferably designed as pneumatic hoses being part of a pipework of a pneumatic distribution network not shown. The pertinent hoses can be made of flexible plastic and are also resistant to high pressure like the pipe section 10. In addition to a pneumatic guide it can also be used to transport other media, such as hydraulic fluids; if required, also pasty media. In particular, the assignable tube pieces 30 can be attached in a detachable manner to the bent tube section 10 according to FIG. 3 using the fittings 18, 20, which will be explained in more detail below with reference to FIGS. 4 to 6.

As is further apparent from FIGS. 1 and 3, the tube length X in the bent portion of the pipe section 10, i.e. between the adjacent sides of the two flange-like extensions 22, 24, has been chosen smaller than the sum of the axial installation lengths Y, Z of both fittings 18, 20 at the associated connection geometries 12, 14, the length determination in turn starting at the respective flange-like widening 22, 24 of the pipe section 10. The relevant installation length X can also be chosen equal to the sums of the named axial installation lengths Y and Z. In this way, the arc connection is designed very compact, and after bending almost no straight cylindrical pipe sections result, as they otherwise exist for other known arc angles, i.e. the arc according to the invention can pass into in the fittings or connecting parts 18, 20 without lips, which aids an obstacle-free media or fluid management, without any media or fluid particles unintentionally settling at the transition points to the fittings. The ratio of bending radius to pipe diameter is also located in a range at the edge of the technically feasible. The ratio of bending radius to pipe diameter is 12.7/5 and for larger sizes 20.5/7, 21.8/9, 33.9/12.5 and 44.3/30.

Depending on the design of individual fittings, which may also be different from the fittings 18, 20, these can be connected to the corresponding connection geometries of the pipe section 10 using means other than beading, for instance by means of pressing, welding or making a clip connection. Furthermore, there is the option of screwing on, which will be explained in more detail in the embodiment of FIGS. 5 and 6.

The fitting 18 shown in FIG. 4 has on the inner peripheral side a shoulder into which an O-sealing ring 32 is attached by clamping as a sealing means. For clamping the o-ring 32, a further clamping insert 34 is provided in the form of a collet whose individual clamping jaws 36 are used to attach the free end of an assignable, inserted hose 30 in the usual way, which is therefore not described in more detail. When inserting the hose 30 in the clamping insert 34, the clamping jaws 36 spread at their end facing the free end 26 of the pipe section 10, and upon insertion of the hose 30 these return to their starting position, shown in FIG. 4, where the hose 30 is clamped. For the clamping insert 34 to remain in the interior of the connection geometry 12, a sleeve part 38 is provided, the inner end of which abuts the free end face of the clamping insert 34 and its other free end 40 forming an inwardly projecting beaded edge 40 used to hold the sleeve part 38 in position on the outer peripheral side of the connection geometry 12. If the beaded edge 40 is not attached too firmly to the connection geometry 12, there is also the option of holding the sleeve part 38 rotatably on the connection geometry 12 in the form of a connection nozzle.

At the other end of the pipe section 10, a screw-in part 42 is fixed on the connection geometry 14 using a hexagonal chamfer 44. Again, a sealing means in the form of a further o-ring 46, this time is arranged in a stepped widening of the connection geometry 14 and is clamped held in sealing position by means of the screw-in part 42, wherein in turn, the screw-in part is held in position on the pipe section 10 by a beading edge 48, which extends over the widening 24 of the connection geometry 14. To protect the other O-ring 46, the pertinent beaded connection is fixed. On its free end, the hexagonal chamfer 44 adjoins a further, third O-ring seal 50, and a piece of a pneumatic hose, not shown in greater detail, can be connected in a sealing manner to a lower male thread 52 of the screw-in part 42. In this way, a media-carrying connection between the two connection parts 18, 20 and the intermediate pipe section 10 is established.

The bent tubular connection element according to FIGS. 5 and 6 will be described only insofar as it differs significantly from the preceding embodiment. In the embodiment according to FIG. 5, the sleeve part 38 is designed as a screw-on part, the female thread of which can be screwed onto a male thread 54 of the connection geometry 12. In the relevant screw-on process, an annular tappet web 56 is used to entrain the clamping element of a hose 30 in the form of the collet 34 and the individual jaws 36 are controlled by control and guide bevels at the free end 26 of the first connection geometry 12 for an opening and closing operation for attaching the hose 30 not shown in FIG. 5 in an obvious manner.

Furthermore, the sleeve part 38 of FIG. 5 has a hexagonal chamfer 58 at its free outer end for the purpose of screwing or rotating movement of the sleeve part 38 by means of a suitable, actuating tool (open-end wrench), not shown.

The screw-in part 42, which in turn is attached to the lower end of the pipe section 10, this time has a lock nut 60 as a counterpart in addition to the hexagonal chamfer 44, which can be connected to the screw-in part 42 via assignable female and male threaded sections at the free upper end of the screw-in part and which is rotatably supported via a snap ring 62 disposed on the pipe section 10 within the lock nut 60 and in an outer recess of the pipe section 10 so as to be able to conduct the screw-on operation on the male thread of the screw-in part 42 without obstacles. In this way, the screw-in part 42, which likewise has a male thread 52 at its lower free end for the purpose of attaching a screw-on hose 30 (not shown), can be attached to the connection geometry 14 of the pipe section 10. In doing so, viewed towards FIG. 5, the free lower end 28 of the pipe section 10 comes into abutment with an inner step 64 of the screw-in part 42. The embodiment according to FIG. 6 corresponds to the embodiment of FIG. 5 with the proviso that instead of a bending angle of 90°, one of 45° is selected for the pipe section 10.

As a standardized standard part, the connection element according to the invention can be used in a variety of different pipework for transporting media, and the individual outer design of the connection element according to the illustrations of FIGS. 3 to 6 illustrates that a substantially closed outer contour is achieved, taking into account the respective fittings 18, 20, such that dirt possibly occurring during operation cannot settle inadvertently on the connection element, and if such dirt particles should occur, they can be easily cleaned from the surface of the connection element. In that regard, the connection element according to the invention will preferably be used in the food industry and in the pharmaceutical industry. 

1. A method for producing a bent tubular connection element using at least the following manufacturing steps: Performing a machining operation for a metallic, rectilinear pipe section (10) of predeterminable length, including connection geometries (12, 14) for receiving separate fittings (18, 20) to connect media-carrying pipework, Performing a bending process for the pipe section machined thus (10) having a predetermined bending radius, preferably of up to 90 degrees, and Mounting the respective fitting (18, 20) to the assignable connection geometry (12, 14) at the end of the pipe section (10).
 2. The method according to claim 1, characterized in that the rectilinear pipe section (10) undergoes lathing as machining processing and that the bending process is a cold forming process.
 3. The method according to claim 1, characterized in that the connection geometries in the two opposite end portions (26, 28) of the rectilinear pipe section (10) receive between them a pipe segment (16) having a constant diameter, which is bent and which at bending process is provided with the largest curvature in the center.
 4. The method according to claim 1, characterized in that lathed connection geometries (12, 14) opposite the pipe section (10) are designed differing from each other.
 5. The method according to claim 1, characterized in that two flange-like widenings 22, 24 of the connection geometries (12, 14) are arranged at the pipe segment (16) of the pipe section (10) having a constant diameter on both sides, which widenings are provided as the widest points of the connection geometries (12, 14), and that the diameter of every connection geometry with respect to this widest point (22, 24) is reduced towards the free end of the pipe section (10).
 6. The method according to claim 1, characterized in that the connection parts (18, 20) after they have been attached to the respective assignable connection geometries (12, 14) of the pipe section (10) limit at least partially at the outer and/or inner circumference of the pipe section (10) a sealing means, preferably in the form of an O-ring seal (32, 46), which is attached by clamping.
 7. The method according to claim 1, characterized in that at least part of the fitting (18, 20) are fixedly or rotatably mounted on the connection geometries (12, 14) of the pipe section (10).
 8. The method according to claim 1, characterized in that the pipe length (X) of the bent part of the pipe section (10) is equal to or less than the sum of the axial installation lengths (Y, Z) of the two fittings (18, 20) on the associated connection geometries (12, 14), the length determination starting from the individual flange-like widening (22, 24) of the pipe section (10).
 9. The method according to claim 1, characterized in that at least one connection geometry (12) of the pipe section (10) is provided with a recess on the inner periphery such that a collet (34) of the connection part (18) is received, which collet is configured to engage at one end part of the pipework to be connected.
 10. A connection element, produced according to claim 1 having a bent, machined pipe section (10), which has connection geometries (12, 14) for fittings (18, 20) arranged at the end, by means of which fittings the connection element can be connected to parts (30) of a media-carrying pipework. 